Linear guide

ABSTRACT

A linear guide comprises a rail ( 1 ) having several running tracks ( 2 ), and a carriage ( 3 ) with at least one sliding element ( 4 ), which is opposite the running tracks ( 2 ) and has an inclined surface ( 5 ) on the side facing away from the rail ( 1 ), where a shiftable adjuster ( 6 ) that is provided between the sliding element ( 4 ) and the carriage ( 3 ) has a surface ( 7 ) resting in shiftable fashion against the inclined surface ( 5 ) of the sliding element ( 4 ). In order to automatically adjust the bearing clearance, the adjuster ( 6 ) is pre-tensioned against the inclined surface ( 5 ) of the sliding element ( 4 ), meaning that a force component results on the sliding element ( 4 ) perpendicular to the running tracks ( 2 ) opposite the sliding element ( 4 ), and the contacting surfaces ( 7, 5 ) of the adjuster ( 6 ) and the sliding element ( 4 ) have corresponding steps, designed such that, due to the pre-tension of adjuster ( 6 ) and with the corresponding clearance, the steps on the surface ( 7 ) of the adjuster ( 6 ) can slide over the steps on the inclined surface ( 5 ) of the sliding element ( 4 ) as it moves in the direction of the running tracks of the rail ( 1 ).

[0001] The invention relates to a linear guide with a rail having several running tracks, and a carriage with at least one sliding element, which is opposite the running tracks and has a surface on the side facing away from the rail that is inclined relative to the running directions of the linear guide, where an adjuster that is provided between the sliding element and the carriage can be shifted in the running directions of the linear guide and has a surface resting in shiftable fashion against the inclined surface of the sliding element.

[0002] A linear guide of this kind is known from the applicant's “DryLin® T” catalogue of August 1998. It comprises an essentially T-shaped rail and a carriage with a correspondingly designed channel. The rail has two first pairs of running tracks that are opposite one another and perpendicular to the normal load direction of the carriage, and one second pair of running tracks that are opposite one another and perpendicular to the first running tracks. Sliding elements made of a highly wear-resistant plastic with a low coefficient of friction are provided in the carriage opposite the running tracks. In order to adjust a clearance both in the normal load direction of the carrier and transverse thereto, the sliding elements opposite the running tracks of the rail, whose surface normal is opposite to the normal load direction of the carriage, and opposite one of the running tracks, whose surface normal is perpendicular to the normal load direction, are of wedge-shaped design, where the associated adjusters are also wedge-shaped in the opposite direction. The adjusters can be pressed against the inclined surface of the sliding elements by means of a setting screw, whereby the associated sliding element, the wider end of which opposite the setting screw is up against an abutment of the carriage, is moved towards the rail and thus reduces the clearance between the carriage and the rail at the corresponding bearing point. By loosening the setting screw, the clearance between the carriage and the rail can be increased at the corresponding bearing point. Expediently, the adjuster is pushed back by a compression spring when the setting screw is loosened.

[0003] Instead of two running tracks, whose surface normals are opposite to the normal load direction of the carriage, the rail can, in case of smaller loads, also have just one, centrally located running track and one corresponding sliding element opposite to it. In contrast to the arrangement described above, the wedge-shaped sliding elements can also be provided at other bearing points of the linear bearing where it is desirable to adjust the clearance.

[0004] In the known linear guides, the clearance is usually adjusted at the factory by the manufacturer. This pre-setting can be made on the basis of the displacement force of the carriage. In many cases, however, is it necessary for the customer to readjust the bearing clearance. Because three bearing points can be readjusted with the help of the setting screws, this adjustment and control must be very precise. There is a risk of excessively increasing or decreasing the clearance of one of the bearing points during readjustment.

[0005] The object of the present invention is to further develop a linear guide of the kind described above, such that it is not necessary to adjust the bearing clearance of the linear guide by means of setting screws or any other adjusting elements that have to be set by the manufacturer and/or customer.

[0006] According to the invention, the object is solved in that the adjuster is pre-tensioned against the inclined surface of the sliding element, meaning that a force component results on the sliding element perpendicular to the running tracks opposite the sliding element, and the contacting surfaces of the adjuster and the sliding element have corresponding steps, designed such that, due to the pre-tension and with the corresponding clearance, the steps on the surface of the adjuster can slide over the steps on the inclined surface of the sliding element as it moves in the direction of the running tracks of the rail.

[0007] As a result of the design according to the invention, when there is excessive clearance, the steps on the surface of the adjuster slide over the corresponding steps on the sliding element until the clearance between the sliding element and the running rack of the rail is reduced to a minimum, such that the edges of the steps of both surfaces lie against one another. In this way, excessive clearance is reduced automatically, without requiring adjustment by means of a setting screw or some other adjusting element.

[0008] Automatic adjustment of the clearance by the adjuster requires the carriage to be loaded such that the existing clearance results between the associated sliding element and the running track of the rail.

[0009] In a preferred configuration of the invention, the steps on the inclined surface of the sliding element have sections that are essentially parallel to the running directions of the linear guide, and sections that rise at an angle of <90° in the direction of the pre-tension of the adjuster. In this context, the steps on the surface of the adjuster that is in contact with the inclined surface of the sliding element can be of corresponding design.

[0010] The angle of the rising sections of the steps is preferably selected such that it is larger than the self-locking angle and smaller than the wedging angle.

[0011] In an expedient configuration of the invention, the step sections running essentially parallel to the running directions of the linear guide decline slightly in the direction of the pre-tension of the adjuster. Due to the decline of these sections, a minimum clearance always exists between the sliding element and the associated running track of the rail. If, because of its pre-tension, the adjuster slides over a step height equal to the remaining clearance between the sliding element and the associated running track of the rail, the clearance increases as the adjuster moves until the steps of the adjuster come up against the steps of the sliding element. The self-adjusting minimum clearance resulting is then equal to the depth of the declining slope of the step sections perpendicular to the running directions of the linear guide.

[0012] Such automatic adjustment of a minimum clearance between the sliding elements and the running tracks of the rail is particularly advantageous when no additional elements of defined elasticity are present to ensure the existence of some clearance. In contrast, if compensation is provided by the system, the declining slope of the essentially horizontal step sections of the sliding element and the adjuster can be dispensed with.

[0013] If a declining slope is provided on the relevant step sections, its height perpendicular to the running directions of the linear guide can be between 0.01 and 0.1 mm.

[0014] Preferably, this height is between 0.01 and 0.05 mm.

[0015] In order to avoid self-locking of the step arrangement, the rising sections of the steps on the inclined surface of the sliding element or the adjuster can have a height perpendicular to the running directions of the linear guide of between 0.02 and 0.2 mm.

[0016] Preferably, this height is between 0.02 and 0.1 mm.

[0017] In order to pre-tension the adjuster, a compression spring can be provided that acts on it parallel to the running directions of the linear guide. To save space, the compression spring is preferably arranged on the side of the adjuster and acts on a transverse projection on said side.

[0018] The contacting surfaces of the carriage, the adjuster and/or the sliding element can be of semi-cylindrical design in order to compensate for non-parallelism of the bearing. For example, the inclined surface of the sliding element can be of semi-cylindrical design and rest against a surface of the adjuster that has a correspondingly concave cross-section.

[0019] In another configuration, the surface resting against the sliding element, or an opposite surface of the adjuster that rests against the carriage, can be of semi-cylindrical design.

[0020] The sliding element is preferably made of a highly wear-resistant plastic with a low coefficient of friction. Optimum results were achieved by pairing such a plastic for the sliding elements with anodised aluminium for the rail.

[0021] With regard to the design of the carriage and the sliding bearing, as well as the arrangement of the sliding pairs comprising a running track of the rail and a sliding element of the carriage, the linear guide can in all other respects be designed like the known linear guides described in the opening paragraphs. In particular, the rail can have two first pairs of running tracks that are opposite one another and perpendicular to the normal load direction of the carriage, and one second pair of running tracks that are opposite one another and perpendicular to the first running tracks. The cross-section of the rail can be essentially T-shaped with a corresponding channel in the carriage, where the sliding pairs are expediently arranged symmetrically about the mid-perpendicular of the linear guide. Other designs for the rail and carriage channel, and other arrangements of the sliding pairs can be used, if this is expedient for special load conditions.

[0022] In a standard configuration of the linear guide, the running tracks of the rails, whose surface normals are opposite to the normal load direction of the carriage, and one of the running tracks, whose surface normals are perpendicular to those of the former running tracks, are each assigned a sliding element with an inclined surface and a correspondingly designed adjuster.

[0023] In order to achieve self-adjustment of the clearance in an arrangement of this kind, the carriage must be loaded relative to the rail in a direction opposite to the normal load direction, so that the existing clearance results between the sliding elements with an inclined surface and the associated running tracks of the rail.

[0024] A practical example of the invention is described in more detail below on the basis of the drawings. The drawings show the following:

[0025]FIG. 1 A longitudinal section through a linear guide with a carriage loaded in direction A,

[0026]FIG. 2 An enlarged view of section B in FIG. 1,

[0027]FIG. 3 A front view in direction C of the linear guide according to FIG. 1,

[0028]FIG. 4 A cross-section along line D-D through the linear guide according to FIG. 1,

[0029]FIG. 5 A longitudinal section through the linear guide with the carriage loaded in direction E,

[0030]FIG. 6 An enlarged view of section B in FIG. 5,

[0031]FIG. 7 A front view in direction C of the linear guide according to FIG. 5, and

[0032]FIG. 8 A cross-section along line D-D through the linear guide according to FIG. 5.

[0033] As shown particularly clearly in FIGS. 1 and 5, the linear guide in the drawing consists of a rail 1 with several running tracks 2, and a carriage 3 with sliding elements 4, which are opposite running tracks 2 and have a surface 5 on the side facing away from rail 1 that is inclined relative to the running directions of the linear guide. Provided between each sliding element 4 and carriage 3 is an adjuster 6, which can be shifted in the running directions of the linear guide, is of wedge-shaped design like sliding element 4, and one surface 7 of which rests in shiftable fashion against inclined surface 5 of sliding element 4.

[0034] As is further shown in the drawings, carriage 3 has essentially cuboid cut-outs 8 extending in the running directions of the linear guide for accommodating sliding element 4 and adjuster 6. Wedge-shaped sliding element 4 and adjuster 6 are arranged in such a cut-out 8 such that their inclined surfaces 5 and 7 rest against one another and the top of adjuster 6 and the bottom of sliding element 4 are parallel.

[0035] The largest face end of sliding element 4 rests against an abutment in carriage 3 (not shown), while adjuster 6 is pre-tensioned by compression spring 9 in the direction of the largest face end of sliding element 4 in one running direction of the linear guide. Due to the pre-tension of adjuster 6, a force component results on sliding element 4 perpendicular to running track 2 of rail 1.

[0036] As shown in more detail in FIGS. 2 and 6, contacting surfaces 5 and 7 of sliding element 4 and adjuster 6 have corresponding steps, where, given appropriate clearance, the steps of surface 7 of adjuster 6 can, due to its pre-tension, slide over the steps of inclined surface 5 of sliding element 4. In load direction A shown in FIG. 1, adjuster 6 is pushed over the steps of sliding element 4 until the remaining bearing clearance is less than the step height. In this context, adjuster 6 is arranged such that, over its possible travel path, its bottom side does not hit rail 1, and its smallest face end does not hit the abutment (not shown) for sliding element 4.

[0037] As shown in more detail in FIG. 2, the steps on inclined surface 5 of sliding element 4 or on adjuster 6 have sections 10 that are essentially parallel to the running directions of the linear guide, and sections 11 that rise at an angle of <90° in the direction of the pre-tension of adjuster 6. The angle of the rising sections is selected such that it is larger than the self-locking angle and smaller than the wedging angle of the linear guide arrangement.

[0038] As shown in detail in FIG. 6, sections 10, running essentially parallel to the running directions of the linear guide, decline slightly in the direction of the pre-tension of adjuster 6. As a result, if the remaining bearing clearance is zero and the step edges of surface 7 of adjuster 6 slide over the step edges of surface 5 of sliding element 4, minimum clearance S indicated in FIG. 6 results when adjuster 6 is shifted further to the next step section due to the pre-tension. This measure ensures that a minimum clearance of S always results when the clearance of the linear guide adjusts automatically.

[0039]FIGS. 3, 4 and 7, 8 show the arrangement on rail 1 and carriage 3 of the sliding pairs, which comprise sliding element 4 and running track 2 of rail 1. Rail 1 and carriage 3 are of essentially symmetrical design, where rail 1 is T-shaped and carriage 3 has a correspondingly shaped channel 12. Rail 1 has two first pairs of running tracks 2 that are opposite one another and perpendicular to normal load direction A of carriage 3, and a second pair of running tracks 2 that are opposite one another and perpendicular to the first running tracks. For the purpose of automatically adjusting a vertical and lateral bearing clearance, running tracks 2, whose surface normals are opposite to normal load direction A of carriage 3, and one of the lateral running tracks are each assigned a sliding element 4 of the kind described above with inclined surface 5 and a corresponding adjuster 6. The other running tracks are assigned essentially cuboid sliding elements 13, which are secured against displacement in carriage 3.

[0040] Surfaces 14 of adjusters 6, which rest against the carriage, and surfaces 15 of sliding elements 13, which rest against carriage 3, are of semi-cylindrical design in order to compensate for non-parallelism in the linear guide by means of corresponding rotation of sliding elements 4 and 13.

[0041]FIGS. 3 and 7 further show line F-F, which results in the longitudinal sections shown in FIGS. 1 and 5.

Linear Guide List of Reference Numbers

[0042]1 Rail

[0043]2 Running track

[0044]3 Carriage

[0045]4 Sliding element

[0046]5 Inclined surface

[0047]6 Adjuster

[0048]7 Surface

[0049]8 Cut-out

[0050]9 Compression spring

[0051]10 Section

[0052]11 Section

[0053]12 Channel

[0054]13 Sliding element

[0055]14 Surface

[0056]15 Surface 

1. Linear guide with a rail (1) having several running tracks (2), and a carriage (3) with at least one sliding element (4), which is opposite the running tracks (2) and has a surface (5) on the side facing away from the rail (1) that is inclined relative to the running direction of the linear guide, where an adjuster (6) that is provided between the sliding element (4) and the carriage (3) can be shifted in the running directions of the linear guide and has a surface (7) resting in shiftable fashion against the inclined surface (5) of the sliding element (4), characterised in that the adjuster (6) is pre-tensioned against the inclined surface (5) of the sliding element (4), meaning that a force component results on the sliding element (4) perpendicular to the running tracks (2) opposite the sliding element (4), and the contacting surfaces (7, 5) of the adjuster (6) and the sliding element (4) have corresponding steps, designed such that, due to the pre-tension of the adjuster (6) and with the corresponding clearance, the steps on the surface (7) of the adjuster (6) can slide over the steps on the inclined surface (5) of the sliding element (4) as it moves in the direction of the running tracks of the rail (1).
 2. Linear guide as per claim 1, characterised in that the steps on the inclined surface (5) of the sliding element (4) have sections (10) that are essentially parallel to the running directions of the linear guide, and sections (11) that rise at an angle of <90° in the direction of the pre-tension of the adjuster (6).
 3. Linear guide as per claim 2, characterised in that the step sections (10) running essentially parallel to the running directions of the linear guide decline slightly in the direction of the pre-tension of the adjuster (6).
 4. Linear guide as per claim 3, characterised in that the step sections (10) running essentially parallel to the running directions of the linear guide decline over a height of between 0.01 and 0.1 mm perpendicular to the running directions.
 5. Linear guide as per claim 4, characterised in that the step sections (10) running essentially parallel to the running directions of the linear guide decline over a height of between 0.01 and 0.05 mm perpendicular to the running directions.
 6. Linear guide as per one of claims 2 to 5, characterised in that the rising sections (11) of the steps on the inclined surface (5) of the sliding element (4) have a height perpendicular to the running directions of the linear guide of between 0.02 and 0.2 mm.
 7. Linear guide as per claim 6, characterised in that the rising sections (11) of the steps on the inclined surface (5) of the sliding element (4) have a height perpendicular to the running directions of the linear guide of between 0.02 and 0.1 mm.
 8. Linear guide as per one of claims 1 to 7, characterised in that the adjuster (6) is pre-tensioned by a compression spring (9) that acts on it parallel to the running directions of the linear guide.
 9. Linear guide as per one of claims 1 to 8, characterised in that the inclined surface (5) of the sliding element (4) is of semi-cylindrical design and rests against a surface (7) of the adjuster (6) that has a correspondingly concave shape.
 10. Linear guide as per one of claims 1 to 8, characterised in that the surface (7) resting against the sliding element (4), or an opposite surface of the adjuster (6) that rests against the carriage (3), is of semi-cylindrical design.
 11. Linear guide as per one of claims 1 to 10, characterised in that the sliding element (4) is made of a highly wear-resistant plastic with a low coefficient of friction.
 12. Linear guide as per one of claims 1 to 11, characterised in that the rail (1) has two first pairs of running tracks (2) that are opposite one another and perpendicular to the normal load direction (E) of the carriage (3), and one second pair of running tracks (2) that are opposite one another and perpendicular to the first running tracks.
 13. Linear guide as per claim 12, characterised in that, of the first running tracks (2), those whose surface normals are opposite to the normal load direction (E) of the carriage (3), and one of the second running tracks (2), are each associated with a sliding element (4) with an inclined surface (5) and an adjuster (6). 